libcurl's TFTP state machine fails to validate state transitions against the requested transfer direction, accepting opening server responses for both reads and writes interchangeably. A malicious TFTP server can respond to a download request in a way that forces the client into transmit mode, prompting libcurl to consume and transmit data from the handle's persistent `CURLOPT_READDATA` pointer - including data remaining from unrelated prior operations, such as an HTTP POST request executed on a reused handle.

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity High

Privileges Required None

Scope Unchanged

Confidentiality Impact Low

Integrity Impact None

Availability Impact None

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Key SSVC decision points have not yet been added.

Affected Vendors & Products

Vendors Products
Curl
  • Curl

No data.

No data.

References
Link Providers
https://curl.se/docs/CVE-2026-92389.html cve-icon cve-icon
https://curl.se/docs/CVE-2026-92389.json cve-icon cve-icon
https://hackerone.com/reports/4022568 cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-92389 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-92389 cve-icon
History

Tue, 20 Oct 2026 20:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in curl. When handling Trivial File Transfer Protocol (TFTP) transfers, a malicious server can trigger information disclosure by responding to a download request in a way that forces the client into transmit mode. Consequently, the client may unintentionally send leftover sensitive data from prior operations on a reused connection handle to the attacker's server. libcurl's TFTP state machine fails to validate state transitions against the requested transfer direction, accepting opening server responses for both reads and writes interchangeably. A malicious TFTP server can respond to a download request in a way that forces the client into transmit mode, prompting libcurl to consume and transmit data from the handle's persistent `CURLOPT_READDATA` pointer - including data remaining from unrelated prior operations, such as an HTTP POST request executed on a reused handle.
Title curl: curl: TFTP direction confusion TFTP direction confusion
References

Sun, 18 Oct 2026 17:00:00 +0000

Type Values Removed Values Added
First Time appeared Curl
Curl curl
Vendors & Products Curl
Curl curl

Sat, 17 Oct 2026 00:30:00 +0000

Type Values Removed Values Added
Description A flaw was found in curl. When handling Trivial File Transfer Protocol (TFTP) transfers, a malicious server can trigger information disclosure by responding to a download request in a way that forces the client into transmit mode. Consequently, the client may unintentionally send leftover sensitive data from prior operations on a reused connection handle to the attacker's server.
Title curl: curl: TFTP direction confusion
Weaknesses CWE-200
References
Metrics threat_severity

None

 cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N'}

threat_severity

Low
cve-icon MITRE

Status: PUBLISHED

Assigner: curl

Published: 2026-10-20T20:21:45.378Z

Updated: 2026-10-20T20:21:45.378Z

Reserved: 2026-09-16T08:12:48.831Z

Link: CVE-2026-92389

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-20T21:17:21.457

Modified: 2026-10-22T16:57:53.407

Link: CVE-2026-92389

cve-icon Redhat

Severity : Low

Publid Date: 2026-10-14T12:00:00Z

Links: CVE-2026-92389 - Bugzilla